Preheat oven to 375°F (190°C) and line a 9x13-inch baking pan with parchment paper.

In a mixing bowl, combine melted butter, granulated sugar, vanilla extract, and salt until blended. Gradually stir in flour until coarse crumbs form. Press two-thirds into the pan.

In another bowl, toss sliced apples with cinnamon and nutmeg. Spread evenly over the crust.

Drizzle caramel sauce over the apple filling, ensuring even distribution.

Sprinkle remaining crumb mixture over the caramel and apples, covering them completely.

Bake for 40-45 minutes until golden brown topping and tender apples. Let cool in the pan for about 30-45 minutes.

Lift out the parchment paper to remove the block, then slice into squares.